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Fair Value Option Elected, Difference Between the Aggregate Fair Value and the Aggregate Unpaid Principal Balance (Detail) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Trading assets $ 6,595us-gaap_TradingSecurities [1]   $ 6,202us-gaap_TradingSecurities [1]
Loans Held-for-sale, Fair Value Disclosure 2,077us-gaap_LoansHeldForSaleFairValueDisclosure   1,892us-gaap_LoansHeldForSaleFairValueDisclosure
Loans Receivable, Fair Value Disclosure 268us-gaap_LoansReceivableFairValueDisclosure   272us-gaap_LoansReceivableFairValueDisclosure
Long-term Debt, Fair Value 1,281us-gaap_LongTermDebtFairValue   1,283us-gaap_LongTermDebtFairValue
Aggregate Fair Value Under Fair Value Option      
Trading assets 2,733us-gaap_TradingSecurities
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateFairValueUnderFairValueOptionMember		   2,610us-gaap_TradingSecurities
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateFairValueUnderFairValueOptionMember
Loans Held-for-sale, Fair Value Disclosure 2,077us-gaap_LoansHeldForSaleFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateFairValueUnderFairValueOptionMember		   1,891us-gaap_LoansHeldForSaleFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateFairValueUnderFairValueOptionMember
Loans Receivable, Fair Value Disclosure 265us-gaap_LoansReceivableFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateFairValueUnderFairValueOptionMember		   269us-gaap_LoansReceivableFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateFairValueUnderFairValueOptionMember
Long-term Debt, Fair Value 1,281us-gaap_LongTermDebtFairValue
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateFairValueUnderFairValueOptionMember		   1,283us-gaap_LongTermDebtFairValue
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateFairValueUnderFairValueOptionMember
Aggregate Unpaid Principal Balance Under Fair Value Option      
Trading assets 2,686us-gaap_TradingSecurities
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateUnpaidPrincipalBalanceUnderFairValueOptionMember		   2,589us-gaap_TradingSecurities
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateUnpaidPrincipalBalanceUnderFairValueOptionMember
Loans Held-for-sale, Fair Value Disclosure 2,005us-gaap_LoansHeldForSaleFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateUnpaidPrincipalBalanceUnderFairValueOptionMember		   1,817us-gaap_LoansHeldForSaleFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateUnpaidPrincipalBalanceUnderFairValueOptionMember
Loans Receivable, Fair Value Disclosure 274us-gaap_LoansReceivableFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateUnpaidPrincipalBalanceUnderFairValueOptionMember		   281us-gaap_LoansReceivableFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateUnpaidPrincipalBalanceUnderFairValueOptionMember
Long-term Debt, Fair Value 1,176us-gaap_LongTermDebtFairValue
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateUnpaidPrincipalBalanceUnderFairValueOptionMember		   1,176us-gaap_LongTermDebtFairValue
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateUnpaidPrincipalBalanceUnderFairValueOptionMember
Fair Value Over/(Under) Unpaid Principal      
Trading assets 47us-gaap_TradingSecurities
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_FairValueOverUnderUnpaidPrincipalMember		   21us-gaap_TradingSecurities
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_FairValueOverUnderUnpaidPrincipalMember
Loans Held-for-sale, Fair Value Disclosure 72us-gaap_LoansHeldForSaleFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_FairValueOverUnderUnpaidPrincipalMember		   74us-gaap_LoansHeldForSaleFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_FairValueOverUnderUnpaidPrincipalMember
Loans Receivable, Fair Value Disclosure (9)us-gaap_LoansReceivableFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_FairValueOverUnderUnpaidPrincipalMember		   (12)us-gaap_LoansReceivableFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_FairValueOverUnderUnpaidPrincipalMember
Long-term Debt, Fair Value 105us-gaap_LongTermDebtFairValue
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_FairValueOverUnderUnpaidPrincipalMember		   107us-gaap_LongTermDebtFairValue
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_FairValueOverUnderUnpaidPrincipalMember
Loans Held For Investment [Member]      
Fair Value, Option, Changes in Fair Value, Gain (Loss) 2us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForInvestmentMember		 [2] 4us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForInvestmentMember		 [3]  
Loans Held For Investment [Member] | Aggregate Fair Value Under Fair Value Option      
Nonaccrual loans 3us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateFairValueUnderFairValueOptionMember
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForInvestmentMember		   3us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateFairValueUnderFairValueOptionMember
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForInvestmentMember
Loans Held For Investment [Member] | Aggregate Unpaid Principal Balance Under Fair Value Option      
Nonaccrual loans 4us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateUnpaidPrincipalBalanceUnderFairValueOptionMember
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForInvestmentMember		   5us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateUnpaidPrincipalBalanceUnderFairValueOptionMember
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForInvestmentMember
Loans Held For Investment [Member] | Fair Value Over/(Under) Unpaid Principal      
Nonaccrual loans (1)us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_FairValueOverUnderUnpaidPrincipalMember
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForInvestmentMember		   (2)us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_FairValueOverUnderUnpaidPrincipalMember
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForInvestmentMember
Loans Held For Sale [Member]      
Fair Value, Option, Changes in Fair Value, Gain (Loss) 12us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForSaleMember		 [2] (1)us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForSaleMember		 [3]  
Loans Held For Sale [Member] | Aggregate Fair Value Under Fair Value Option      
Nonaccrual loans     1us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateFairValueUnderFairValueOptionMember
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForSaleMember
Loans Held For Sale [Member] | Aggregate Unpaid Principal Balance Under Fair Value Option      
Nonaccrual loans     1us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_AggregateUnpaidPrincipalBalanceUnderFairValueOptionMember
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForSaleMember
Loans Held For Sale [Member] | Fair Value Over/(Under) Unpaid Principal      
Nonaccrual loans     0us-gaap_FairValueOptionLoansHeldAsAssetsAggregateAmountInNonaccrualStatus
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= sti_FairValueOverUnderUnpaidPrincipalMember
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForSaleMember
Deposits [Member]      
Fair Value, Option, Changes in Fair Value, Gain (Loss)   3us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_FairValueByMeasurementBasisAxis
= us-gaap_DepositsMember		 [3]  
Mortgage Servicing Income [Member] | Loans Held For Investment [Member]      
Fair Value, Option, Changes in Fair Value, Gain (Loss) 0us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForInvestmentMember
/ us-gaap_IncomeStatementLocationAxis
= sti_MortgageServicingIncomeMember		 0us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForInvestmentMember
/ us-gaap_IncomeStatementLocationAxis
= sti_MortgageServicingIncomeMember		  
Mortgage Servicing Income [Member] | Loans Held For Sale [Member]      
Fair Value, Option, Changes in Fair Value, Gain (Loss) 0us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForSaleMember
/ us-gaap_IncomeStatementLocationAxis
= sti_MortgageServicingIncomeMember		 0us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_FairValueByMeasurementBasisAxis
= sti_LoansHeldForSaleMember
/ us-gaap_IncomeStatementLocationAxis
= sti_MortgageServicingIncomeMember		  
Mortgage Servicing Income [Member] | Deposits [Member]      
Fair Value, Option, Changes in Fair Value, Gain (Loss)   $ 0us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_FairValueByMeasurementBasisAxis
= us-gaap_DepositsMember
/ us-gaap_IncomeStatementLocationAxis
= sti_MortgageServicingIncomeMember		  
[1] Includes trading securities pledged as collateral where counterparties have the right to sell or repledge the collateral of $1,207 million and $1,316 million at March 31, 2015 and December 31, 2014, respectively
[2] Changes in fair value for the three months ended March 31, 2015 exclude accrued interest for the period then ended. Interest income or interest expense on trading loans, LHFS, LHFI, and long-term debt that have been elected to be carried at fair value are recognized in interest income or interest expense in the Consolidated Statements of Income.
[3] Changes in fair value for the three months ended March 31, 2014 exclude accrued interest for the period then ended. Interest income or interest expense on trading loans, LHFS, LHFI, brokered time deposits, and long-term debt that have been elected to be carried at fair value are recognized in interest income or interest expense in the Consolidated Statements of Income.